Interpretive Summary: An established cattle market in the Northern Great Plains (NGP) creates a demand for feed grains including corn grain and silage. However, dryland corn production is limited by drought conditions that increase the risk of crop failure. Altering the planting row configuration and adjusting the seeding rate have reduced the risk of yield loss in other areas, but these areas typically receive greater rainfall than the average 12-14 inches annual precipitation of the NGP. A study was initiated in 2007 to determine the impact of seeding rate and row configuration on dryland corn yield and water use in the NGP. Two sites in north eastern Montana were planted to corn at four rates (10-, 15-, 20-, and 25,000 plants/acre) in conventional 24 inch-spaced rows or in a skip row configuration with every third row skipped. At all seeding rates, total biomass yield was greater in conventional than in skip row corn. However, trends for unshelled ear yield were inconsistent and any differences between conventional and skip row configurations were small. Yield (biomass and unshelled ear) showed an inverse relationship with seeding rate. Furthermore, a greater proportion of total biomass was made up of grain (unshelled ears) as planting rates decreased. Soil moisture monitored at a depth of 36 inches in the skipped row during the growing season indicated little difference between 10,000 and 25,000 seeding rates. Conversely, readings taken at 18 inch depth suggested the 25,000 seeding rate depleted available soil moisture earlier in the season, limiting grain fill potential. Data from the first year of this study suggests that for areas with low rainfall, potential improvements in corn yield and yield quality can be made by adjusting seeding rates to 10,000 seeds/acre or lower.

Technical Abstract: An established cattle market in the Northern Great Plains (NGP) creates a demand for feed grains including corn grain and silage. However, dryland corn production is hampered by the risk of crop failure due to drought conditions. Altering the row configuration and seeding rate have reduced the risk of yield loss in other areas, but these typically receive greater rainfall than the average 12-14 in annual precipitation of the NGP. A study was initiated in 2007 to determine the impact of seeding rate and row configuration on dryland corn yield and water use in the NGP. Two sites in north eastern Montana were planted to corn at four rates (10, 15, 20, and 25k plants/ac) in conventional 24 in rows or in a skip row configuration with every third row skipped. Soil water content in skip row plots was monitored during the growing season via neutron probe access tubes. At all seeding rates, total biomass yield was greater in conventional than in skip row corn. However, trends for unshelled ear yield were inconsistent and any differences between conventional and skip row configurations were small. Yield (biomass and unshelled ear) showed an inverse relationship with seeding rate. Furthermore, a greater proportion of total biomass was made up of grain (unshelled ears) as planting rates decreased. Soil moisture monitored at a depth of 36 in in the skipped row during the growing season indicated little difference between 10k and 25k seeding rates. Conversely, readings taken at 18 in depth suggested the 25k seeding rate depleted available soil moisture earlier in the season, limiting grain fill potential. Data from the first year of this study suggests that for areas with low rainfall, potential improvements in corn yield and yield quality can be made by adjusting seeding rates to 10k plants/ac or lower.